Circulating fluidized bed boilers comprise a furnace and a particle separator in flow connection with an upper portion of the furnace to separate particles from exhaust gas discharged from the furnace. At least a portion of the separated particles is returned back from the particle separator to a lower portion of the furnace via a return channel. A heat exchange chamber comprising heat exchange surfaces embedded in a slow fluidized bed of particles is often arranged in the return channel. Such a heat exchange chamber with a fluidized bed of particles is a relatively heavy construction, the supporting of which requires special measures. The furnace and the particle separator of a large scale circulating fluidized bed boiler plant are usually top-supported from a supporting construction of the plant. According to conventional practice, the heat exchange chamber is either bottom-supported or it is integrated in a common structure with a side wall of the furnace. A bottom-supported heat exchange chamber requires complicated measures to compensate for differential thermal expansions of the units, as shown, for example, in international publication WO 2013/041764. A heat exchange chamber integrated to a side wall of the furnace, such as the one shown in U.S. Pat. No. 5,526,775, may cause lack of space for other systems to be assembled to the lower portion of the furnace.
European patent document EP 2 361 148 B1 discloses an assembly of a particle separator and a heat exchange chamber made as an integrated water tube construction supported to hang from the supporting structure of the boiler. This construction may be difficult to manufacture and to assemble, and the close integration may limit the possibilities to separately optimize the sizes and structures of the particle separator and the heat exchange chamber.
European patent document EP 1 259 758 B2 discloses an assembly comprising a particle separator module and a heat exchange chamber module in which the heat exchange chamber module is suspended from the particle separator module by means of suspension means comprising steam tubes. This construction is relatively simple, but it may still be relatively difficult to assemble, and it may limit the possibilities to separately optimize the sizes and structures of the particle separator and the heat exchange chamber.
An object of the invention is to provide an assembly of a particle separator module and a heat exchange chamber module, a circulating fluidized bed boiler with such an assembly, and a method of installing such an assembly, in which at least a portion of the above-mentioned and other problems of the prior art are minimized or eliminated.